Motor



Patented Mr, 12, 1942 UNITED STATES PATENT- OFFICE Herbert 0. Bowen, Detroit,

Hydraulic Brake Company,

of California corporation Mich, assignor to Detroit, Mich., a

Application December 5, 1938, Serial No. 244,081

8 Claims. (Cl. fill-54.6)

This invention relates to brakes, and more particularly to motors for actuating the friction elements of brakes.

The invention comprehends a fluid pressure actuated motor of the compound type including low and relatively high pressure producing means, and fluid pressure actuated means for rendering one pressure producing means ineffective during actuation of the other.'

An object of the invention is to provide a simple and effective fluid pressure actuated motor of compact structure.

Another object of the invention is to provide a fluid pressure actuated motor including low and high pressure producing means, one nested in the other so as to conserve space.

A feature of the invention is a motor including a pair of pistons, one reciprocable within the other.

Another feature of the invention is a fluid pressure actuated motor including a pair of pistons,

one movable in the other, and means for directing the flow of fluid to the head of one of the pistons and then to the head of the other piston.

Other objects and features of the invention will appear from the following description taken in connection with the drawing forming a part of this specification, and in which,

Fig. 1 is a vertical, sectional view of a brake taken just back of the head of the drum, illustrating the invention as applied;

Fig. 2 is a sectional view, substantially on line 2-2, Fig. 1; and

Fig. 3 is a sectional view, substantially on line 33, Fig. 2.

Referring to the drawing for more specific details of the invention, In represents a fixed support or backing plate adapted to be secured to an axle or to an axle housing, and I2 represents a rotatable drum associated with the backing plate and adapted to be secured to a wheel.

An anchor 14 suitably arranged on the backing plate has pivotally mounted thereon a friction element or brake shoe l6 connected as by an adjustable link 18 to another friction element or brake shoe 20. The shoes l6 and 20 are substantialy alike in structure, each including a web 22, supporting a rim 24 having secured thereto a friction lining 26 for cooperation with the drum. I

The shoes are supported on the backing plate by conventional steady rests 28 and 30, and are connected by a 'retractile spring 32 for returning the shoes to their position of rest upon conclusion of a braking operation. The shoe I6 is porting the the resistance of has a port 58 communicating connected by a sprin'g 34 to a fixed support 36 arranged on the backing plate, and the shoe 20 is connected by a spring 38 toa fixed support 40 also arranged on the backing plate. The springs 34 and 38 serve to move the shoes from the drum upon conclusion of a braking operation. It is, of course, to be understood that suitable stops may be arranged on .the backing plate for supshoes when in retracted position or at rest.

An actuating means for the shoes includes a fluid pressure actuated motor 42 fixedly secured to the backing plate and suitably connected to the shoe 20. The motor is operative to actuate the shoes into engagement with the drum against the rectractile springs so as to effectively retardrotation of the drum.

The motor 42 includes a cylinder 44 having a chamber 46 and a valve chamber 48 arranged concentrically to one another. The chamber 46 has an intake port 50 valve chamber 52, and a port 54 normally closed as by a bleeder screw 56. The valve chamber 52 with an intake port for the cylinder. A check valve 62 in the valve chamber 52 .controls the communication, and the intake port 60 is connected by a conduit 64 to a suitable source of fluid pressure.

The valve chamber 48 has an enlarged portion 66 providing an annular shoulder 68, and seated on this shoulder'is an annular disk 10 having a valve seat 12. The disk is held against displacement by a hollow plug 14 threaded in the enlarged portion of the chamber. The plug has a circumferential groove 16 registering with a passage 18 communicating with the intake port 66 of the cylinder, and a plurality of apertures arranged in the groove provide communications between the groove and the interior of the plug. The plug also has a port 82 opening to the atmosphere.

A piston 84 reciprocable in the hollow plug 14 is seated on a heavy spring 86. This piston has attached to its head a rod 88 extending through the bottom of the chamber 48 well into the chamber 46, and a sealing cup 90 sleeved on the rod is held on the head of the piston as by a light spring 92 interposed between the cup and the disk 10. The rod 88 has thereon a valve 94 suitable for cooperation l0, and sleeved on the rod is asealing cup 96 held on the bottom of the chamber 48 as by a light spring 98. The rod also has an axial passage Hi0 communicating at one end with a diametrical passage I62, and its other end with a communicating with a with the seat 12 in the disk diametrical passage I04. The passage I02 opens into the chamber 48, and the passage I 04 opens into a chamber to be hereinafter described.

A compound piston reciprocable in the chamber includes a shell piston I06 having a head I08 provided with an opening receiving the rod 88. The piston I06 has on its head I08 a sealing cup IIO embracing the rod, and a light spring II2 interposed between the cup and the bottom of the chamber 46 serves to retain the cup against displacement. A piston II4 reciprocable in the shell has an axial recess II 6 receiving the free end of the rod 88, and the recesshas a port II8 opening to the atmosphere. The piston II4 provides in conjunction with theshell piston I06 a chamber I20 communicating with the axial passage I in the rod 88 by way of the passage I04. A sealing cup I22 sleeved on the rod is seated on the back of the head I 08 of the shell piston I06, and another sealing cup I24, also sleeved on the rod is seated on the head of the piston II 4, and a light spring I26 interposed between these cups serves to retain them against displacement. The

piston II4 has a rod I28 terminating in .a clevis I30, and the clevis is attachedto the force-applying end of the shoe 20. H

'In a normal operation of the brake, fluid under pressure enters the cylinder throughthe intake passage I8, the groove I6 and the apertures 80 into the hollow plug 14, thence past the valve into the chamber 48, and from thischamber through the passage I02, the passages I00 and I04 into the chamber I20, resulting in movement of the piston I I4 and initial actuation of the friction elements of the brake.

- formed by the pistons to As the pressure on the fluid increases, the piston 84 recedes, and this results in closing the valve 94 and trapping fluid in the chamber I20,

and, upon closing the valve 94, the pressure on the fluid cracks the check valve 62, resulting in admission of fluid under pressure into the chamber 46 and the consequent movement of the piston I06. The pistons I06 and H4 now move as a single unit, and actuate the friction elements with effective braking force.

Upon conclusion of the braking operation, the pressure on the fluid is released, whereupon the valve 94 cracks, and fluid returns from the chamber I20 through the passages I00, I02 and I04 to the chamber 48 and also from the chamber 46 past the cup 96 to the chamber 48, thence past the valve 94, through the plug I4, the apertures 80, the groove I6 and intake passage I8 to the source of supply, and their retracted positions under the influence of the retractile springs.

While this invention has been described in connection with certain specific embodiments, the principle involved is susceptible of numerous other applications that will readily occur to persons skilled in the art. The invention is, therefore, to be limited only as indicated by the scope of the appended claims.

Having thus described the various features of the invention, what I claim as new and desire to secure by Letters Patent is,

1. A fluid pressure actuated motor comprising a cylinder having a large chamber and a small chamber, a fluid intake having a passageway leading to the small chamber and a valve controlled passageway leading to the large chamber, a pair of pistons reciprocable in the large chamber between the close the by-pass upon attaining a predetermined pressure in the small chamber to trap fluid in the chamber between the pistons, said intake valve responsive to open at a higher pressure on the fluid and thereby admit fluid to the large chamber so as to actuate the pairs of pistons as a single unit.

2. A fluid pressure responsive motor comprising a cylinder-having a large chamber and a small chamber, a fluid intake for the cylinder, a pair of relatively movable pistons one within the other reciprocable in the large chamber, a chamber formed by the pistons, valve mechanism for controlling the flow of fluid under pressure through the small chamber to the chamber initially actuate one of the pistons and responsive to increase in fluid pressure within the small chamber to thereafter trap fluid in the chamber formed by the pistons, and another valve mechanism responsive to further increase in fluid pressure in the fluid intake to thereby admit the passage of fluid under pressure into the large chamber to actuate the pistons as a unit.

3. A fluid pressure actuated motor comprising a cylinder having a large chamber and a small chamber, a hollow piston reciprocable in the large chamber, a piston reciprocable in the hollow piston, a variable chamber between the pistons, means for introducing into the small chamber, means for introducing fluid from the small chamber into the variable chamber, and means eifective upon attaining a predetermined pressure in the small chamber for trapping fluid in the variable chamber, and means effective upon attaining a predetermined pressure in the small chamber to transfer the pressure on the fluid to the head of the hollow piston.

4. A fluid pressure actuated motor comprising a cylinder having a large chamber and a small the pistons are returned to ber one movable within the other, a variable chamber between the pistons, means for by-passing fluid through one of the pistons to the chamchamber, a compound piston reciprocable in the large chamber, a variable chamber between the parts of the compound piston, means for introducing fluid under pressure into the variable chamber, and means in the small chamber for trapping fluid in the variable chamber and means effective thereafter to transfer the pressure on one of the pistons to the other.

5. A fluid pressure actuated motor comprising a large chamber and a small chamber, a hollow piston reciprocable in the large chamber, a piston reciprocable in the hollow piston, a variable chamber between the pistons, means for introducing fluid under pressure into the small chamber and the variable chamber, a valve in the small chamber operative upon attaining a predetermined pressure on the fluid to trap fluid in the variable chamber, and means effective thereafter for admitting fluid under pressure to the large chamber.

6. A fluid pressure actuated motor comprising a large chamber, a small chamber and a passage connecting the chambers, a hollow piston reciprocable in the large chamber, a piston reciprocable in the hollow piston, a variable chamber between the pistons, a valve in the small chamber having a stem extending through the passage, the large chamber, and the variable chamber, said stem. having a passage therethrough providing a communication between the small chamber and the variable chamber controlled by the valve, means for admitting fluid under pressure into the small chamber, means in the small pistons, and means operative to fluid under pressure I Fhamber operative to close the valve upon attainmg a predetermined pressure, and means effective thereafter for admitting fluid under increased pressure into the large cylinder.

7. A fluid pressure actuated motor comprising a cylinder having a large chamber, a small chamber, a passage connecting the chambers, an inlet for the small chamber and a controlled inlet for the large chamber, a hollow piston reciprocable in the large chamber, a piston reciprocable in the hollow piston, a variable chamber between the pistons, a valve in the small chamber having a stem supported by the pistons and extending through the passage, the hollow piston and the variable chamber, said. stem having a passage therethrough providing a communication between the small chamber and the variable chamber, a collapsible cup for control of the passage between the large chamber and the small chamber, and a piston in the small chamber for closing the valve upon attaining a predetermined pressure.

8. A fluid pressure actuated motor comprising a cylinder having a large chamber and a small chamber, a hollow piston reciprocable in the large chamber, a piston reciprocable in the hollow piston, a variable chamber between the pistons, a valve in the small chamber, a hollow stem on the valve providing a communication between the small chamber and the variable chamber, the valve operable to control the communication, means for the admission of fluid under pressure into the small chamber, means in the small chamber operative to close the valve upon attaining a predetermined pressure, and a valve in the wall of the cylinder operable thereafter to admit fluid into the large chamber.

HERBERT C. BOWEN. 

